Three-phase electric furnace for manufacturing aluminium-silicon alloys

ABSTRACT

In an electric furnace relationship between the bath diameter &#39;&#39;&#39;&#39;d,&#39;&#39;&#39;&#39; the lining height &#39;&#39;&#39;&#39;h&#39;&#39;&#39;&#39; and the distance between the electrode axes &#39;&#39;&#39;&#39;1&#39;&#39;&#39;&#39; is such as to form a common reaction zone for reducing metal oxides of the charge and to provide for free discharge of the metal being produced.

United States Patent [1 1 Brusakov et al.

[ Feb. 5, 1974 THREE-PHASE ELECTRIC FURNACE FOR MANUFACTURING ALUMINIUM-SILICON ALLOYS [76] inventors: Jury Ivanovich Brusakov,

Novo-lzmailovsky prospect, 37, kv. 42, Leningrad; Nikolai Nikolaevich Sirotkin, ulitsa Bela Kuna, 5, kv. 228, Leningrad; Vasily Pavlovich Kiselev, ulitsa Lensoveta, 48, kv. 10, Leningrad; Dmitry Vladimirovich llinkov, ulitsa Tregubenko, l3, kv. 5, Zaporozhie; Mikhail Pavlovich Avdeev, Irkitskoi oblasti 7, kvartal, 30, kv. 7, Shelekhev; Semen Panteleevich Marin, ulitsa 40 let Sovetskoi Ukrainy, 86, kv. 53, Zaporozhie; Alexandr Ivanovich Shkarupa, ulitsa Patrioticheskaya, 74, kv. 45, Zaporozhie; Boris Ottovich Veisman, ulitsa 40 let Sovetskoi Ukrainy, 40a, kv. 27, Zaporozhie; Vladimir Nikolaevich Lebedev, prospekt Lenina, 159, kv.

33, Zaporozhie; Nikolai Pavlovich Gavrilenko, Pravy bereg, ulitsa Dudykina, 7, kv. 8, Zaporozhie, all of USSR.

[22] Filed: Sept. 8, 1972 21 Appl. No.: 287,567

Related US. Application Data [63] Continuation of Ser. No. 174,381, Aug. 24, 197i,

abandoned.

[30] Foreign Application Priority Data Nov. 11, 1970 U.S.S.R 1485652 [52] US. Cl. 13/9 [51] Int. Cl F27b 14/14, H05b 7/00 [58] Field of Search l3/9; 75/10, 11

[56] References Cited UNITED STATES PATENTS 3,2l3,l78 lO/l965 Sem 13/9 X Primary Examiner-Roy N. Envall, Jr. Attorney, Agent, or Firm-Dennis O. Kraft [5 7] ABSTRACT In an electric furnace relationship between the bath diameter d," the lining height h and the distance between the electrode axes 1 is such as to form a common reaction zone for reducing metal oxides of the charge and to provide for free discharge of the metal being produced.

2 Claims, 2 Drawing Figures THREE-PHASE ELECTRIC FURNACE FOR MANUFACTURING ALUMINIUM-SILICON ALLOYS This is a continuation of application Ser. No. l74,38l, filed Aug. 24, 1971, and now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to the equipment to be used in the electrothermal process of manufacturing aluminum-silicon alloys, and more particularly to a three-phase electric furnace for manufacturing aluminium-silicon alloys.

The present invention is most advantageous when applied to manufacturing aluminium-silicon alloys produced by directly reducing metal oxides of the charge in an electric furnace.

The invention may be also advantageously used for the production of cristalline silicon, high silicon ferrous alloys and in other electrothermal processes characterized by high power consumption.

Widely known in the art is a three-phase electric furnace for manufacturing aluminium-silicon alloys, comprising a circular bath which is internally lined with carbon blocks, carbon electrodes, the longitudinal axes of the electrodes extending through the apices of an equilateral triangle formed by the electrodes, and means to move the electrodes in a vertical plane, The inside diameter of the bath in such a furnace does not exceed 4.9 times the electrode diameter, the electrode interaxes being of 2.l 2.25 times the electrode diameter and greater, the the height of the bath carbon lining as measured from the furnace hearth being more than one electrode diameter.

When using the furnaces having the abovementioned relationship between geometrical dimensionsof the bath for manufacturing aluminium-silicon alloys, great difficulties are encountered which are due to specific technological features of the process.

As a result of high power consumption and temperature necessary for reducing metal oxides of the charge, reaction spaces within the bath of an electric furnace disposed around each one of the electrodes are of small crossectional dimensions. When using prior art. furnaces, these zones areseparated from each other and disposed far from the discharge opening in the furnace and to fuse the bath. As a result, the productivity is reduced, and the performance characteristics are deteriorated.

SUMMARY OF THE INVENTION plished by the provision of a three-phase eIEctriE Rr nace, comprising a circular bath which is internally lined with carbon blocks, carbon electrodes, the longitudinal axes of the electrodes extending through the apices of an equilateral triangle formed by said electrodes, and means to move the electrodes in a vertical plane, wherein, according to the present invention, relationship between the inside diameter of the bath d, the height of the carbon lining h" and the distance between the longitudinal axes of the electrodes 1 are such as to form a common reaction zone for reducing lining. This specific feature makes discharge of the alloy through several discharge openings. Furthermore, due to high electric conductivity of the charge used in manufacturing aluminium-silicon alloys, considerable currents flow through the space between the electrodes and the carbon lining of an electric furnace. As a result, considerable amount of the power supplied to the furnace is released as heat in these zones of the furnace, whereby power concentration in the underelectrode zone of the furnace is decreased resulting in an intensive superficial fusion of metal oxides of the charge with consequent formation of silicon carbidec. These products having greater specific gravity as compared to that of the alloy, they are progressively accumulated on the furnace hearth under the metal melts layer where a further reduction thereof becomes difficult. As the slag is being accumulated, the penetration of the electrodes into the charge is reduced. The discharge of the alloy becomes more difficult. In order to provide for free metal discharge in prior art furnaces, it was necessary to interrupt charging periodically every 3 7 days metal oxides of the charge and to provide for free discharge of the metal being produced.

With this embodiment optimum performance characteristics in manufacturing aluminium-silicon alloys are achieved with the inside diameter of the bath d of 3.5 4 times the electrode diameter, the distance between the electrode axes l of 1.8- 2.1 times the diameter thereof, and with the height of the internal lining of the bath not exceeding 0.33 of the electrode diameter.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described with reference to the specific embodiment thereof and to the accompanying drawings, in which:

FIG. 1 shows longitudinal section of a three-phase electric furnace for manufacturing aluminium-silicon alloys according to the present invention;

FIG. 2 is a section along the line llll of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A furnace for manufacturing aluminium-silicon alloys comprises a circular bath, carbon electrodes, and means to move the electrodes.

The bath of the furnace for manufacturing aluminium-silicon alloys comprises a metal casing l which is internally lines with chamotte bricks. The furnace hearth 2 and lateral walls 3 made of chamotte bricks inside the furnace are lined with carbon blocks.

Mounted in the furnace are three carbon electrodes 5, the longitudinal axes of said electrodes extending through the apices of an equilateral triangle formed by said electrodes.

The distance between the axes of the electrodes 5 is 1.8 2.1 times the diameter thereof.

The electrodes are moved by mechanical means 6 during the fusion.

The height h of the lateral lining 4 does not exceed 0.33 of the electrode diameter.

The inside diameter of the bath d as measured be tween carbon blocks 4 is 3.5 4 times the electrode diameter.

Three taps 7 are made in the bath lining, the taps being arranged at the level of the carbon hearth 2 oppositely to each one of the electrodes 5.

The charge 8 is fed into the furnace through charging conduits (not shown) or by means of a special charging apparatus. The level of the charge 8 in the furnace is established in accordance with the operational capacity thereof.

In operation, a reaction zone 9 is formed around each electrode 5, the reduction of metal oxides of the charge taking place within said zone.

With the distance between the longitudinal axes of the electrodes of 1.8 2.1 times the diameter thereof the reaction zones 9 contact each other thus forming a common reaction zone, thereby reducing slag formation with respective reduction of the amount of slag being deposited on the furnace hearth which would otherwise hamper the alloy discharge. Free discharge of the alloy is also favoured by reduction of the inside diameter of the bath to 3.5 4.0 times the electrode diameter, whereby the tap length can be reduced, together with reduction of superficial fusion of metal oxides of the charge and avalanching thereof in the tap zone, thereby preventing the tap from being clogged with slag or under reduced charge.

The furnace according to the invention was tested, and the following results were obtained;

The furnace productivity was increased by 89 percent, the specific consumption of the charge and power being reduced by 9.6 percent and 26.6 percent respectively.

Continuous performance of furnaces was achieved.

We claim:

1. A three-phase electric furnace for manufacturing aluminum-silicon alloys by reducing metal oxides in a charge, and comprising: a circular furnace bath having a substantially flat furnace hearth bottom and upwardly inclined walls; carbon blocks for lining the internal surface of said bath to define a reaction depth of said bath measured from the top of said walls to the exposed surface of said carbon blocks lining the bottom of said bath; movable substantially circular carbon electrodes disposed in said bath so that the longitudinal axes of said electrodes are substantially normal to the bottom surface of said bath, said electrodes being arranged in relation to one another so that if straight lines are projected between the longitudinal axes of said electrodes in a plane normal to the direction thereof said straight lines are seen to form an equilateral triangle with said axes passing through the apices thereof; means for positioning said electrodes so as to establish a preselected relationship between said reaction depth, the distance between said axes and the inside diameter of said bath and the diameter of said electrodes, wherein the inside diameter of said bath is greater than the diameter of said electrodes, the distance between said axes is greater than the diameter of said electrodes, and said reaction depth does not exceed a fixed fraction of the diameter of said electrodes, whereby a common reaction zone is formed around said electrodes for reducing metal oxide of the charge and providing for free discharge of metal produced.

2. A furnace according to claim 1, wherein said preselected relationship is established so that the inside diameter of the bath is 3.5 to 4.0 times greater than the electrode diameter, the distance between said electrode axes is 1.8 to 2.1 times greater than the diameter thereof, and said reaction depth does not exceed 0.33

of the electrode diameter. 

2. A furnace according to claim 1, wherein said preselected relationship is established so that the inside diameter of the bath is 3.5 to 4.0 times greater than the electrode diameter, the distance between said electrode axes is 1.8 to 2.1 times greater than the diameter thereof, and said reaction depth does not exceed 0.33 of the electrode diameter. 